Harbor Freight DC inlet and Y pipe usage

[Carlos]

We're going to be re-arranging the shop space (new tools, bigger projects, plus she has agreed to park the car outside and leave space for the important stuff). As part of that we'll have to re-design the DC. I'm thinking I will probably add a separator or cyclone setup of some sort.

The HF DC has a Y connector on the inlet that splits to two 4" hoses. I think the basic inlet size is around 5". I'm wondering if I should go with that size or slightly larger to the separator/cyclone, then split into 4" out of that unit? Have others hooked up this DC in this way?

[Popeye]

I use a seperator with all 4" lines, with the other half of the "Y" left capped. Been using it this way for a year or so with good results.


Here is the whole setup. http://bt3gallery.cpu-etc.com/main.php?g2_itemId=1980
Pat

[LarryG]

I don't have a separator, but if it'll help, I found that the bell of a 4" S&D fitting makes a good fit into the HF unit's inlet if you wrap it with a strip of foam weatherstripping:



The fitting is secured with a series of short, round-headed bolts (nuts to the outside) around the flange on the impeller cover. BTW, that 5" stovepipe mod from the impeller outlet to the bag ring is worth doing, too. More pictures here.

[windmill]

I have the HF unit as well. I used a metal 5"-to-4" reducer over the DC opening, and secured it with a hose clamp and foil tape. The black flexible hose is a smidge too small to fit over the reducer, but if you heat it up with a hair dryer for a minute it's perfect. A clamp keeps this one in place as well.

You should be able to find the reducer in the HVAC section at a home improvement store.

I've used a trash can separator with great success, between that and the canister filter I've been very happy with the whole DC setup. No cleaning out cloth bags, and with the separator the plastic bag only fills up twice a year. You should check out Phil Tien's baffle design if you're building a separator

I could be completely wrong here, but it might have been better for me to run 5" hose from the trash can separator to the DC, but keep the rest of the ducting at 4". This keeps the velocity in the pipe high enough to move the chips, but then forces the velocity to drop in the trash can (same amount of air, larger opening). This should help reduce the scrubbing (i.e. pulling it out of the can into the bag). But this is only a theory.

[Carlos]

Interesting. Never thought about improving the outlet side. Isn't it 5" already?

On the inlet side I was thinking that 5" (or whatever the actual inlet side is) would give me better flow. Or is the DC too low-powered to use that much diameter?

[LCHIEN]

Carlos, it's 5" at the impellor intake split into two 4".
My interpretation of the tables and discussion on Bill Pentz's website make me believe 4" is too small and 6" is too large for the HF DC ducting. So 5" is near optimal - lower restriction loss yet sufficient velocity. Unfortunately 5" piping components are much harder to find than 4" and 6". I have proposed going dual, paralleled 4" as an alternative to 5".

[LarryG]

Interesting. Never thought about improving the outlet side. Isn't it 5" already?

If you're referring to my stovepipe mod ... yes, the hose from the impeller outlet to the bag ring is 5", but a piece of hard pipe of the same diameter stovepipe is a BUNCH smoother on the inside than is the hose.

[Carlos]

Unfortunately 5" piping components are much harder to find than 4" and 6".

We have a local store with a strong supply of 5" hose and pipe, which is what actually got me to thinking about this. I don't think materials will be an issue, so I'm looking for optimum solutions.

Larry, good point, I'll look at some options to improve smoothness on that.